Glycine betaine mitigates cadmium toxicity in plants via redox homeostasis and osmotic adjustment

Cadmium (Cd) stress constitutes a significant issue in agricultural soil, inflicts lethal damages to plants and posing a serious risk to public health as it enters the food chain. This review addresses the cause of Cd toxicity, its numerous forms and absorption mechanism via various transporters and their detrimental impacts on plants. At high level, Cd interacts with cellular molecules leading to overproduction of reactive oxygen species. Under Cd stress, plants naturally synthesize various compatible solutes to enhance the plant's stress tolerance and glycine betaine (GB) is one of such solutes which act as osmoprotectant in plants. The Cd causes oxidative damage to the cells, resulted in changes in morphological attributes, physiological processes etc. and it is indispensable to alleviate Cd toxicity. To mitigate the harmful impacts of Cd, plants adapt self-regulating tolerance mechanism by producing naturally occurring osmolytes and phytochelatins (PCs). Biosynthetic pathway of GB and GB-mediated tolerance mechanism via redox homeostasis, osmotic adjustment, and mechanism of compartmentalization of Cd into the vacuole, the role of genetic engineering in GB biosynthesis in crop plants through which plants can improve their stress tolerance have been discussed. Amalgamation of this strategy must be implemented in the market with synchronization of farmers into cooperatives. This will be beneficial for the improvement in soil, plant and human health alongwith the reduction of Cd toxicity in environment. Further, this strategy must be used by government and non-government agencies, which is the most economical approach to apply at the farmer level.